// compile: c99 -o indytex indytex.c -lglut -lXmu -lGLU -lGL -lX11
//
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <unistd.h>
#include <GL/glut.h>

//#define USE_GLUT_TIMER

#define WIDTH 320
#define HEIGHT 240

time_t cur_time = 0;
int frames = 0;
int display_state = 2;

GLuint tex_id = 0;

void
gl_error_print(void)
{
	GLenum err;

	if ((err = glGetError()))
		printf("glError: %d\n", err);
}

void
keyboard_event(unsigned char key, int x, int y)
{
	if (key == 27)
		exit(0);

	switch (key - '0') {
	case 0:
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		display_state = 0;
		glDisable(GL_TEXTURE_2D);
		break;
	case 1:
		display_state = 1;
		glDisable(GL_TEXTURE_2D);
		break;
	case 2:
		display_state = 2;
		glEnable(GL_TEXTURE_2D);
		glColor3f(1.0, 1.0, 1.0);
		break;
	}
}

#ifdef USE_GLUT_TIMER
void
timer_event(int data)
{
	glutPostRedisplay();
	glutTimerFunc(30, timer_event, 0);
}
#endif

void
display(void)
{
	time_t new_time;
	float fps;
	int diff;

	switch (display_state) {
	case 0:
		break;
	case 1:
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		glBegin(GL_POLYGON);
			glColor3f(1, 0, 0); glVertex3f(-0.6, -0.75, 0.5);
			glColor3f(0, 1, 0); glVertex3f(0.6, -0.75, 0);
			glColor3f(0, 0, 1); glVertex3f(0, 0.75, 0);
		glEnd();
		break;
	case 2:
		glBegin(GL_QUADS);
			glTexCoord2f(0.0, 1.0);
			glVertex3f(-1, -1, 0);
			glTexCoord2f(1.0, 1.0);
			glVertex3f(1.0, -1, 0);
			glTexCoord2f(1.0, 0.0);
			glVertex3f(1.0, 1.0, 0);
			glTexCoord2f(0.0, 0.0);
			glVertex3f(-1, 1.0, 0);
		glEnd();
		break;
	}

	glutSwapBuffers();

	new_time = time(NULL);
	if (new_time != cur_time) {
		diff = new_time - cur_time;
		fps = frames / (diff * 1.0);
		cur_time = new_time;
		frames = 0;

		printf("FPS: %.2f\n", fps);
	} else
		frames++;

	gl_error_print();

#ifndef USE_GLUT_TIMER
	glutPostRedisplay();
#endif
}

void
gl_init(void)
{
	glDisable(GL_DEPTH_TEST);
	glShadeModel(GL_FLAT);
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
	glHint(GL_FOG_HINT, GL_FASTEST);
	glDisable(GL_POLYGON_SMOOTH);
	glDisable(GL_BLEND);
	glDisable(GL_ALPHA_TEST);

	glEnable(GL_TEXTURE_2D);
}

void
texture_init(void)
{
	int x, y;
	char r, g, b;
	char *ptr, *tex_buf;

	tex_buf = malloc(256 * 256 * 3);
	for (y = 0; y < 256; y++) {
		r = y;
		ptr = tex_buf + 256 * 3 * y;
		for (x = 0; x < 256; x++, ptr += 3) {
			b = x;
			g = x / 2 + y / 2;
			ptr[0] = b;
			ptr[1] = g;
			ptr[2] = r;
		}
	}
	glGenTextures(1, &tex_id);
	glBindTexture(GL_TEXTURE_2D, tex_id);

	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
/*
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
	glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
*/

	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 256, 256, 0, GL_BGR,
		     GL_UNSIGNED_BYTE, tex_buf);
}

int
main(int argc, char* argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);

	glutInitWindowPosition(600, 100);
	glutInitWindowSize(WIDTH, HEIGHT);
	glutCreateWindow("Indy Texture Performance Test");

	glutDisplayFunc(display);
	glutKeyboardFunc(keyboard_event);

#ifdef USE_GLUT_TIMER
	timer_event(0);
#endif

	cur_time = time(NULL);

	gl_init();
	texture_init();

	gl_error_print();

	glutMainLoop();
}